Preparation of monohaloacetyl halides

ABSTRACT

A process for the preparation of monohaloacyl halides by halogenating ketenes in the presence of an alicyclic carbonate.

United States Patent [1 1 Bissing et al.

[ 1 Sept. 11, 1973 PREPARATION OF MONOHALOACETYL HALIDES Inventors:Donald E. Bissing; Virgil W. Gash,

both of Ballwin, Mo.

Related US. Application Data Continuation-impart of Ser. No. l92,647,Oct. 26, I971, abandoned.

US. Cl 260/544 Y Int. Cl. C07c 53/14, C07c 51/58 Field of Search 260/544Y [56] References Cited FORElGN PATENTS OR APPLlCATlONS 782,773 9/1957Great Britain 260/544 Y Primary ExaminerLorraine A. Weinberger AssistantExaminer-Richard D. Kelly Att0rneyNeal E. Willis, John L. Young et al.

[57] ABSTRACT A process for the preparation of monohaloacyl halides byhalogenating ketenes in the presence of an alicyclic carbonate.

15 Claims, No Drawings PREPARATION OF MONOHALOACETYL HALIDES Thisapplication is a continuation-in-part of copending application Ser. No.192,647 filed Oct. 26, 1971, now abandoned.

This invention relates to the preparation of monohaloacyl halides by theliquid phase halogenation of ketenes. More particularly, this inventionrelates to the halogenation of ketenes in the presence of a solvent or areaction medium that inhibits or prevents the formation of polyhaloacylhalides and minimizes the formation of acyl halides. The term halogen asused herein includes chlorine, bromine, iodine and halogen halides suchas iodine monochloride, iodine monobromide, bromine monochloride and thelike.

The liquid phase halogenation of ketene is well known but the previouslyknown methods of conducting this reaction have resulted in the formationof monohaloacetyl halides contaminated with a considerable proportion ofdihaloacetyl halides and polyhalogenated by-products. These earliermethods utilized such solvents as chlorinated benzenes, nitrobenzene,carbon tetrachloride, chloroacetyl chloride, acetyl chloride,l,2-dichloroethane, acetonitrile, benzonitrile, nitromethane and variousother solvents. Each of these solvents had a common shortcoming; thatis, they all resulted in the formation of an appreciable amount ofdihaloacetyl halide, together with the desired product, monohaloacetylhalide. In some of these solvents, the undesired trihaloacetyl halideswere also formed. The dihalo derivatives have no commercial utility andtheir separation from the monohalo derivative is expensive and timeconsuming. For example, dichloroacetyl chloride has a boiling point ofapproximately 107C whereas monochloroacetyl chloride has a boiling pointof about 105C. This proximity of the boiling points of these twocompounds renders their separation exceedingly difficult and also addsan expensive and uneconomical step to the halogenation process whenutilized in the previously known solvents.

The monohaloacetyl halides produced by the process of this invention arevaluable intermediates in the production of herbicidalalpha-haloacetanilides and other products. By contrast, thecorresponding diand trihaloacetyl halides have nocommercialsignificance. in other words, they are present merely asdiluents which detract from the efficacy of the commercially valuablemonohaloacetylhalides. The severity of the problem is evidenced by thefact that all commercially available chloroacetyl chloride iscontaminated with appreciable amounts of dichloroacetyl chloride, and insome instances the dichloroacetyl chloride content is as great as sixpercent.

in accordance with the present invention, the disadvantages of the priorart solvents are overcome by the halogenation of a ketene in thepresence of an alicyclic carbonate of the formula ana came a mm C II Theprocess of the present invention encompasses the halogenation of ketene,i.e., CH,=C=0, as well as substituted ketenes such as methyl ketene,dimethyl ketene, ethyl ketene, diethyl ketene, phenyl ketene, diphenylketene and the like.

Ethylene carbonate and other l,2- and LES-alicyclic carbonates can beused alone or in any combination for the purposes of the presentinvention. Suitable carbonates include, for example, l,2-propylenecarbonate, l,2-butylene carbonate, l,3-propylene carbonate, 1,3-butylene carbonate, 2,2-dimethyl-l,3-propylene carbonate,l,2-diethyl-l,3-propylene carbonate, l,2- dimethylethylene carbonate,l-chloromethylethylene carbonate, l,2-diethylethylene carbonate and thelike. When an unsaturated carbonate is introduced into the system, theunsaturation is satisfied by the addition of the halogenating agent totwo adjacent carbon atoms originally joined by the double bond.Alicyclic carbonates having seven or more ring members, such as 1,4-butylene carbonate and the like, could be beneficial solvents in theprocess of the present invention, but are of little practical value incomparison to the five and six membered ring carbonates of thisinvention.

In carrying out the process of the present invention, the ketene and thehalogen are introduced into the car bonate solvent medium where theyreact to form monohaloacyl halides which are separated from the reactionmedium by conventional means such as distilla tion, preferably atreduced pressure. The process is amenable to either continuous or tobatch type operation. The operating conditions under which the reactionis conducted are not critical but it is preferred to maintain themwithin specified limits to maximize the yield of the monohaloacylhalides. In essence, it is only necessary that the carbonates are liquidunder reaction conditions. Because of pratical considerations, however,the reaction is normally conducted within the approximate temperaturerange of 50C to 150C at a pressure from about 50 mm. Hg. to about 2atmospheres. In most instances, however, it is preferred to operate at atemperature between about 0C and about 1 10C at a pressure between aboutmm. and about 760 mm. The reaction of the halogen and the ketene willprogress to form substantially pure monohaloacyl halides regardless ofthe mole ratio of the reactants. The advantages of the present inventionare more fully realized, however, when the mole ratio of halogen toketene is maintained between about 0.821 and about 2.021 and optimumresults are obtained with mole ratios of halogen to ketene between about1:1 and about 1.3:1. The presence of an alicyclic carbonate of thepresent invention in the reaction medium minimizes the fonnation of acylhalides'and substantially eliminates the formation of dihaloacyl halidesand other polyhalogenated byproducts.

In accordance with the present invention, the carbonate can constitutesubstantially all or only a minor portion of the reaction medium. Thebenefits of the present invention are most pronounced when the solventweight ratio is high but substantial benefits are realized even when thecarbonate is present in relatively small amounts. The undesirablepolyhalogenated acyl halides are formed only in minute amounts even whenthe reaction medium contains a low ratio of carbonate solvent and theyare almost completely excluded at the higher ratios. The weight ratio ofthe carbonate to the sum of the carbonate and the product, i.e., thesolvent weight ratio, can vary from about 0.05:1 to about 0.99:1. Infact, during the normal course of a batch reaction, the solvent weightratio diminishes with the formation of the product which becomes mixedwith the is high, i.e., greater than 95 percent, and the amount ofdihaloacyl halide is minimized, giving a haloacyl purity of greater than98 percent. In Example 4, the yield of bromoacetyl bromide is above 85percent with a purity carbonate forming the reaction medium. In thepracof greater than 99 percent.

. .-..A -L...-.. .FABLE I Example Number Solvent Tetrachloro-1,3-butylene Ethylene Chloromethyl- Phenylethylene ethylene carbonatecarbonate carbonate ethylene carbonate carbonate Pressure (mm.Hg)...-.... 150 760 100 100 760. Temperature C.) 30 3 40 -25 20-25.Ketene Ketene Methyl ketene....... Ketene Ketene Phenyl ketene. HalogenChlorine. Chl0rine-. Bromine. Chlorine Chlorine. Solvent amount(parts)-.. 150.. 58.... 150.. 100.. 50. Halogen amount (parts).. 110..218.. 110. 26. Keteno amount (parts). 59... 47.... 52-.. 42... 3B.Ilaloacylhalide Chloroacolyl chl0rlde-... 2ehl0r0-pr0pionylBromoacetylbromide Chloroacetyl chloride... 2chloro-2-phenylchloride.acetyl chloride. Dihaloucylhalide.. Dlchloroacetyl chloride.2,2dichloroproplonyl Dibromoacetyl bromide... Dichloroacetyl chloride.2,24iichloro-2- chloride. pkllilen ygacetyl c on e.

tice of the continuous process, the solvent weight ratio can bemaintained constant or varied to desired levels.

The invention will be more clearly understood from the followingdetailed description of specific examples thereof. In these examples andthroughout the specification all proportions are expressed in parts byweight unless otherwise indicated.

EXAMPLE 1 About 200 parts (SOLVENT AMOUNT) of ethylene carbonate(SOLVENT) were charged into a suitable reaction vessel, maintained at anabsolute pressure of about 100 mm. Hg. (PRESSURE) and provided with agas outlet, temperature recording means and two gas spargers below thelevel of the carbonate. With the reaction medium maintained at atemperature of approximately 45-50C (TEMPERATURE), ketene (KE- TENE) andchlorine (HALOGEN) were introduced through separate spargers at constantand substantially equimolar rates. After about 2% hours, the addition ofthe reactants was terminated. About 188 parts (HALO- GEN AMOUNT)chlorine and about 95 parts (KE- TENE AMOUNT) ketene had been addedduring the course of the reaction. At the termination of the reaction,the ratio of the solvent to the sum of the solvent and product was about0.44. The reaction mixture was essentially ethylene carbonate,chloroacetyl chloride (HALOACYL HALlDE) with minor amounts ofdichloroacetyl chloride (DIHALOACYL HALIDE) and acetyl chloride. Upondistillation to separate the pure chloroacetyl chloride, the molepercent yield of chloroacetyl chloride was determined to be 96 percent,together with about 1.9 percent acetyl chloride and about 2 percentdichloroacetyl chloride.

Although in this example the reaction mass was agitated, agitation isnot necessary in the halogenation process of this invention. Whenbromine is the halogen, it is preferred to agitate the reaction mass butgood'results are also obtained without agitation.

Following the general procedure of Example l but with conditions andmaterials changed as noted in Table l the indicated products areobtained. The line titles of Table l are shown in parenthesis in thedescription of Example 1 where appropriate.

In Examples 2, 3, 5 and 6 the yield of haloacyl halide EXAMPLE 7 To areactor fitted with spargers and temperature recording means was added235 parts of 1,2-propylene carbonate. Chlorine and ketene were spargedinto the reactor at 100 mm. of Hg pressure with the temperaturemaintained at 20 to 25C for approximately 182 minutes. A slight excessof chlorine (with respect to ketene) was maintained in the propylenecarbonate solution during the course of the reaction. Fractionation andanalysis of the products showed a chloroacetyl chloride yield of 94.6percent and a dichloroacetyl chloride yield of 0.6 percent. The acetylchloride yield was 4.8 percent. The chloroacetyl chloride purity was99.2 percent. Solvent recovery was substantially quantitative.

in order to illustrate the advantages of the solvents of the presentinvention, the procedure of the foregoing Example l was substantiallyduplicated using other solvents. The percent yields thus obtained,together with the results of Examples 1 and 7 are tabulated below inTable ll.

TABLE II Dichloro- Solvent Chloroacet 1 Ace l ace l Recov- Chlori eChlori e Chlori e ered Solvent Yield Purity (91;) Yield Yield Example I96 98 1.9 2 95 Example 7 94.6 99.2 4.8 0.6 95 Ethyl 92 96 5 3 78 AcetateCarbon Tetra- 42 69 43 15 chloride l,2-Dichloro- 35 53 M 24 ethyleneMethyl 91 94 4 4 88 Acetate Aceto- 46 83 47 7 66 nitrile Nltro- 48 74 39i3 75 methane n-Butyl 82 l5 3 84 Acetate n-Hexyl 81 95 15 4 83 AcetateBenzo- 87 94 9 4 92 nitrile By comparison of the same procedureutilizing other solvents, it is self-evident that the solvents of thepresent invention substantially suppress the formation ofpolychloroacetyl chlorides and minimize the formation of acetylchloride. The separation of pure chloroacetyl chloride from acetylchloride and the solvent by fractionation presents no problem because ofthe wide divergence in boiling points of these compounds.

The improvement effected by the carbonate solvents is also evidenced inthe better than 90 percent recovery of the solvent for recycle purposes.This provides greatly improved economy of operation. It is also evidentfrom the high percent recovery of the solvents that the beneficialeffect exerted by these solvents is due to the intrinsic nature of theirchemical structure.

The beneficial results of the present invention are obtained in likemanner with other carbonates under consideration as well as with theother aforementioned halogenating agents. Bromine can be introduced intothe system as the liquid, combined with the carbonate in solution, or inthe gaseous state below the surface of 1 the reaction mass. in mostinstances it is preferred to conduct brominations in accordance withthis invention by using a solution of bromine in the carbonate solvent.When iodine monochloride is used as the halogenating agent, it can becharged into the reactor by dissolving it in the carbonate solvent andthen adding the resulting solution to the system.

Although the invention has been described with respect to specificmodifications, the details thereof are not to be construed aslimitations except to the extent indicated in the following claims.

What is claimed is:

l. A process for the preparation of a monohaloacyl halide whichcomprises reacting a ketene and a halogen selected from the groupconsisting of chlorine, bromine, iodine, iodine monochloride, iodinemonobromide and bromine monochloride in the presence of an alicycliccarbonate of the formula C ll 0 wherein R, R, R, R, R, and R areindependently hydrogen, halogen, methyl, chloromethyl or ethyl, and n isan integer of 0 or 1.

. 2. A process in accordance with claim 1 wherein R, R, R, R, R and Rare hydrogen.

3. A process in accordance with claim 1 wherein n is 1.

4. A process in accordance with claim 1 wherein n is 0.

5. A process in accordance with claim 1 wherein the carbonate isethylene carbonate.

6. A process in accordance with claim 1 wherein the carbonate isethylene carbonate and the halogen is chlorine.

7. A process in accordance with claim 1 wherein the carbonate isethylene carbonate and the halogen is bromine.

8. A process in accordance with claim 1 wherein the carbonate isl,2-propylene carbonate.

9. A process in accordance with claim 1 wherein the carbonate is1,3-propylene carbonate.

10. A process of claim 1 wherein the carbonate is tetrachloroethylenecarbonate.

11. A process of claim 1 wherein the carbonate is 1,3-butylenecarbonate.

12. A process of claim 1 wherein the carbonate is chloromethylethylenecarbonate.

13. A process of claim 1 wherein the carbonate is phenylethylenecarbonate.

14. A process of claim 1 wherein the ketene is unsubstituted ketene.

15. A process of claim 14 wherein the halogen is chlorine.

# t i i

2. A process in accordance with claim 1 wherein R, R1, R2, R3, R4 and R5are hydrogen.
 3. A process in accordance with claim 1 wherein n is
 1. 4.A process in accordance with claim 1 wherein n is
 0. 5. A process inaccordance with claim 1 wherein the carbonate is ethylene carbonate. 6.A process in accordance with claim 1 wherein the carbonate is ethylenecarbonate and the halogen is chlorine.
 7. A process in accordance withclaim 1 wherein the carbonate is ethylene carbonate and the halogen isbromine.
 8. A process in accordance with claim 1 wherein the carbonateis 1,2-propylene carbonate.
 9. A process in accordance with claim 1wherein the carbonate is 1,3-propylene carbonate.
 10. A process of claim1 wherein the carbonate is tetrachloroethylene carbonate.
 11. A processof claim 1 wherein the carbonate is 1,3-butylene carbonate.
 12. Aprocess of claim 1 wherein the carbonate is chloromethylethylenecarbonate.
 13. A process of claim 1 wherein the carbonate isphenylethylene carbonate.
 14. A process of claim 1 wherein the ketene isunsubstituted ketene.
 15. A process of claim 14 wherein the halogen ischlorine.